Maths · Applications of derivatives: Rate of change of quantities, monotonic-Increasing and decreasing functions, Maxima and minima of functions of one variable

=\tan ^{-1} x-x \) is

\( f(x)=\tan ^{-1} x-x \) is \( _{-1} \) \( \boldsymbol{R} \)

  • A. increasing to \( R \)
  • B. decreasing to \( R \)
  • C. increasing on \( R^{+} \)
  • D. increasing on \( (-\infty, 0) \)

Step-by-step solution

Compute f'(x) = 1/(1+x^2) - 1 = -x^2/(1+x^2) ≤ 0 for all real x, with equality only at x=0. Hence f is decreasing on entire R.
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